This disclosure relates to electrical test probes that may be used to test integrated circuits and other electronic assemblies, and to interconnect subassemblies in equipment.
During testing, integrated circuit (IC) packages are removably mounted in sockets, which in turn are mounted on a circuit substrate, commonly referred to as a device-under-test board, or DUT board. The sockets house individual electrical test probes for electronically connecting each terminal of a device to be tested to an individual circuit path on the DUT board. The DUT board is in turn electrically connected to computerized test equipment.
Other electronic assemblies are typically tested in fixtures where a test probe is mounted in a mechanically or vacuum activated mechanism and are brought to engage the assembly to be tested. The fixtures are also connected to computerized test equipment.
It is desirable to have a high integrity signal path from the test equipment to the device being tested and for the overall resistance of the signal path to be low and consistent. This is also true for each segment of the overall signal path including the test probe housed in the test socket.
The electrical test probes can also be used as an interconnect mechanism between two electronic subassemblies. In operation, an electrical signal passes from one probe tip, through the barrel, and out the other probe tip. The test probe is usually put in a housing that separates the two electronic subassemblies. It is desirable to have constant, predictable impedance, a low consistent resistance, and a broad range of frequencies that can pass through the electrical test probes.
In all cases, it is desirable to have a high integrity signal path from the test equipment to the device being tested and for the overall resistance of the signal path to be low and consistent. This is true for each segment of the overall signal path including the test probe. Hence, a continuing need exists for reliable, low contact resistance, electrical test probes, and methods of making the same.